sanity: filter the build-all test for ethernet

Ethernet build-all test was not being filtered base on RAM size so
build step LINK was failing with "region `RAM' overflowed by 192
bytes" error when running daily sanitycheck.

Added filter so this test is not attempted for boards with smaller
RAM such as quark_d2000_crb, which was causing daily build failure

Change-Id: I4ed3bef4f1c78e83890331db34fb1f2b2b066414
Signed-off-by: Genaro Saucedo Tejada <genaro.saucedo.tejada@intel.com>